In the past, it was almost impossible to input various information (for example, photographing date, weather, magnification ratio, and printed sheet number) into a silver halide photographic light-sensitive material (hereinafter abbreviated to a light-sensitive material) when photographing with a camera, and it was only possible to optically input a photographing date.
Also when printing on photographic material, inputting information regarding the light-sensitive material itself is entirely impossible and has become a large obstacle to rapid processing and cost reduction.
Inputting various information into light-sensitive material will be a very important means for improving and simplifying the operation of a camera in the future. Magnetic recording is important as an information input means therefor in terms of capability of arbitrary input and output and inexpensiveness, and therefore the use of magnetic recording for this purpose has been investigated.
Magnetic recording layers and the input and output process therefor make it possible to incorporate various information into a light-sensitive material, which was difficult in the past. It has become possible to input and output into the magnetic recording layer, for example, the photographing date; the weather conditions; the illumination conditions; the photographing conditions, such as minification/magnification ratio; the reprinted seat number; a film portion, if any, which must be zoomed; a message; and printing conditions. Further, it may be possible to utilize such layer as signal input/output means used when information is input directly into a TV/video image to form an image.
U.S. Pat. Nos. 3,782,947, 4,279,945, and 4,302,523 describe a magnetic recording layer having a transparency necessary for a light-sensitive material during photographing, the magnetic recording layer being provided on the backside of the light-sensitive material which includes a transparent support. These magnetic recording layers operate based upon pertinent selection of the amount and size of a magnetic substance contained in the magnetic layer. Further, a system for signal input into this magnetic recording layer is disclosed in International Patent Publications 90-4205 and 90-04212.
These patents were the origin which promoted research directed to improving the transparency and magnetic recording performance (i.e., S/N ratio) of a magnetic recording layer. It has been discovered that the classification of particle of magnetic substances into a desired size by a dispersing method, can provide a light-sensitive material which is transparent and has a high S/N ratio. This is described in JP-A-5-88283.
In recent years, however, it has been discovered that the transparency which can be achieved by the patents described above is limited and in applications such as, for example, reversal film (a positive film), a large color density originated in the magnetic substance contained in the magnetic recording layer causing a problem.
Further, the graininess of an emulsion used in light-sensitive material has been improved in recent years. However, a new problem has been created in that the graininess obtained by the methods of the above patents deteriorates the graininess of the emulsion which has been improved at a great cost. This is due to the presence of the magnetic recording layer.
In order to obtain an optically transparent magnetic recording layer having a high S/N ratio and which has good graininess, a manufacturing process by which the orientation of the magnetic substance is increased is required.